JPS587148B2 - air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an air conditioner, in particular, a compressor, a user-side heat exchanger, an expansion valve, and a heat source-side heat exchanger connected by refrigerant piping,
This relates to an air conditioner in which the refrigerant flowing through the heat source side heat exchanger is evaporated by heat exchange with the heat source water, and the user side heat exchanger performs heating, and the purpose is to increase the heat source water temperature during heating. An object of the present invention is to provide an air conditioner that can maintain both the pressure and degree of superheat of suction gas of a compressor and the pressure of discharge gas at normal values even if the temperature changes over a wide range, such as from 15°C to 40°C. .

Generally, in buildings with multiple rooms, one system of circulating water piping is installed in each heat source side heat exchanger of the air conditioner placed in each room, so that the heat source water can be shared. A recuperative air conditioning system is used.

However, in this type of air conditioning system, the circulating heat source water is cooled by the heat source side heat exchanger of the air conditioner that performs heating operation, while it is heated by the heat exchanger of the air conditioner that performs cooling operation.

Therefore, no matter how the load ratio between cooling and heating changes in the entire air conditioning system, each air conditioner will perform cooling or heating operation as necessary, and in order to improve heat recovery performance, the heat source water The temperature can be varied over a fairly wide range, for example from 15°C to 4°C.
The temperature must be varied over 0°C.

Therefore, in an air conditioner that performs heating operation, when the temperature of the heat source water reaches a high temperature such as 40° C., the evaporation pressure of the refrigerant in the heat source side heat exchanger increases more than necessary, and the degree of superheating of the intake gas also increases.

As a result, the condensation pressure in the heat exchanger on the user side rises abnormally, causing overload on the compressor and causing burnout of the compressor motor coil.Also, the abnormal rise in discharge gas temperature causes decomposition and lubrication of the refrigerant. There are problems such as carbonization of oil or activation of high pressure switches and safety valves, which prevent normal operation.

As a measure to prevent abnormal increases in the pressure and degree of superheating of suction gas and discharge pressure in air conditioners in which the heat source side heat exchanger is heated by heat source water during heating, as in the past, the heat source side heat exchanger is used. A method that changes the heat transfer area of the vessel and a method that uses liquid injection have been proposed. That is, in the former method, a branch pipe is branched from the outlet side of the temperature-sensitive expansion valve and connected to an intermediate position of the heat exchanger on the heat source side, and a solenoid valve is connected to the branch pipe, so that the heat source water temperature rises and the suction pressure increases. Furthermore, when the discharge pressure increases, the solenoid valve is opened to bypass the refrigerant flowing out from the temperature-sensitive expansion valve to the intermediate position of the heat source side heat exchanger. This method attempts to maintain normal suction pressure and discharge pressure by heating only the latter half from the intermediate position using heat source water.

However, with this method, there is a problem that the connection structure of the branch pipe at the intermediate position of the heat source side heat exchanger becomes complicated. There is a problem that the temperature cannot necessarily be controlled within a predetermined range.

On the other hand, in the latter method, a liquid injection tube is connected from the liquid pipe part of the refrigerant piping to the suction side of the compressor, and when the heat source water temperature rises, the liquid refrigerant is passed through the liquid injection tube to the compressor. This method injects gas into the suction side and cools the suction gas to maintain it at an appropriate degree of superheat.

However, although this method can prevent overheating of the intake gas,
The suction and discharge pressures cannot be adequately controlled, resulting in problems such as burnout of the compressor motor and activation of the high pressure switch.The present invention was devised in view of the above problems. In an air conditioner comprising a user-side heat exchanger and a heat source-side heat exchanger, the refrigerant in the heat source-side heat exchanger is evaporated by heat exchange with heat source water, and heating is performed by the user-side heat exchanger, A constant pressure expansion valve whose valve opening is controlled by the refrigerant pressure at the outlet of the heat exchanger during heating is provided on the inlet side of the heat source side heat exchanger during heating; One end of a liquid injection tube is connected to the side liquid pipe, and the other end of the liquid injection tube is connected to the outlet side of the heat source side heat exchanger during heating, and the tube is provided with a solenoid valve and a liquid injection valve. When the temperature of the discharged gas is higher than a predetermined value, the temperature-sensitive detection part detects the temperature of the discharged gas of the machine, and the electromagnetic valve is opened, and the temperature of the intake gas between the position where the other end of the tube is connected and the compressor is detected. By adjusting the opening degree of the liquid injection valve, both the pressure and temperature of the intake gas and the discharge gas can be reliably maintained at normal values even if the temperature of the heat source water changes over a fairly wide range during heating. This is done to ensure stable operation.

Embodiments of the present invention will be described in detail below based on the drawings.

In the drawing, 1 is a compressor, 2 is a four-way switching valve, 3 is a user-side heat exchanger that becomes a condenser during heating and an evaporator during cooling, 4
5 is a cooling expansion valve; 5 is a check valve installed in a bypass pipe 6 bypassing the expansion valve 4; 7 is a heating expansion valve; 8 is a check valve installed in a bypass pipe 9 bypassing the expansion valve 7. a check valve, and 10
is a heat source side heat exchanger which serves as an evaporator during heating and a condenser during cooling, and these devices are connected by refrigerant piping 11.

Reference numeral 12 denotes a circulating water pipe in which water is circulated by a pump (not shown) to flow through the heat source side heat exchanger 10, and to exchange heat with the refrigerant flowing through the heat exchanger 10.

In the heating operation and the cooling operation, the refrigerant is circulated in the direction of the solid line arrow and the dotted line arrow, respectively, to the user side heat exchanger 3.
This is done by condensing and evaporating, respectively.

However, in the above explanation, the heat source side heat exchanger 10 is
Although there is a known heat pump type air conditioner that heats with heat source water during heating and cools during cooling, the present invention provides an air conditioner having such a structure, in which a constant pressure expansion valve is used as the heating expansion valve 7. At the same time, the liquid injection tube 14 is branched from the liquid pipe 13 which becomes high pressure during heating in the refrigerant pipe 11 and is connected to the gas pipe 20 which becomes low pressure during heating and communicates with the suction port of the compressor 1. A solenoid valve 16 and a liquid injection valve 17 are interposed in the tube 14 to control the amount of liquid injection so that the degree of superheating of the refrigerant on the suction side is appropriate even if the temperature of the heat source water changes during heating. It was designed to be controlled.

The constant pressure expansion valve 7 is provided with a pressure detecting section 15 on the outlet side of the heat source side heat exchanger 10 during heating, and controls its valve opening degree according to the refrigerant pressure of the detecting section 15. The heat exchanger 1 operates as if closing the valve opening.
The refrigerant pressure at the 0 outlet is automatically controlled to a predetermined value.

That is, even if the temperature of the heat source water rises to a high temperature of, for example, 40° C. during heating, and the refrigerant pressure on the outlet side of the heat exchanger 10 increases considerably, the pressure increase in the detection unit 15 Since the opening degree of the constant pressure expansion valve 7 is reduced, the refrigerant pressure at the outlet side of the heat exchanger 10 becomes the predetermined value, and therefore the suction gas pressure of the compressor 1 and the discharge gas pressure both reach the predetermined pressure value. It will be retained.

Then, when the heat source water temperature decreases again, the heat exchanger detection unit 1
5, the opening degree of the expansion valve 7 is increased, and the refrigerant pressure on the outlet side of the heat exchanger 10 is maintained at the predetermined value.

Further, the electromagnetic valve 16 opens when the discharge gas temperature rises above a predetermined value and closes when the discharge gas temperature falls below a predetermined value according to a command from a temperature sensing portion 18 provided on the discharge side of the compressor 1. In addition, the liquid injection valve 17 is provided with a temperature sensing portion 19 on the suction side of the compressor 1, and operates to open the valve as the degree of superheating of the suction gas increases, thereby controlling the amount of injection. This maintains the degree of superheating of the intake gas at an appropriate value.

That is, when the heat source water temperature is sufficiently low during heating, the solenoid valve 1
6 is closed and injection is not performed, but when the heat source water temperature rises to a high temperature of 40°C, for example, heat exchanger 1 closes and is not injected.
The degree of superheating of the refrigerant flowing out from the compressor 1 is considerably large, and the discharge gas discharged from the compressor 1 is also in a state higher than a predetermined value. The detection unit 19 detects this and widens the valve opening of the valve 17 to inject a considerable amount of liquid refrigerant into the suction side to bring the suction gas to an appropriate degree of superheating and also bring the discharge gas temperature to an appropriate value. It can be maintained.

As described above, according to the embodiment of the present invention, even if the temperature of the heat source water changes over a wide range during heating, the constant pressure expansion valve 7 ensures that the refrigerant on the outlet side of the heat source side heat exchanger 10 is at an appropriate pressure. This makes it possible to maintain the suction pressure and thus the discharge pressure at a predetermined value, and also to maintain the degree of superheat of the suction gas at an appropriate value by injecting liquid through the liquid injection tube 14. be.

In the above explanation, we used a heat pump type air conditioner.
Even in the case of an air conditioner exclusively for heating, the pressure and degree of superheat of the intake gas and the pressure of the discharged gas can be maintained at predetermined values in a similar manner.

As described above, according to the present invention, even if the temperature of the heat source water changes over a wide range, the suction pressure and therefore the discharge pressure are maintained at a predetermined value by the constant pressure expansion valve, and liquid injection is performed on the suction side of the compressor. By maintaining the degree of superheating of the suction gas at an appropriate value, the temperature of the discharged gas can be maintained at an appropriate value, thereby eliminating carbonization of the lubricating oil and burnout of the compressor motor coil, as well as the high-pressure switch, This allows normal operation without the safety valve operating.

Further, according to the present invention, when used in a heat recovery type air conditioning system, the fluctuation range of the heat source water temperature can be widened considerably, and an external device installed in the air conditioning system to maintain the temperature of the heat source water within a predetermined range. The operation time of the heating source and external cooling source can be shortened, and energy savings can be realized.

[Brief explanation of the drawing]

The drawing is a refrigerant and circulating water piping system diagram showing an embodiment of the present invention. 1...Compressor, 7...Constant pressure expansion valve, 1
0...Heat source side heat exchanger, 11...Refrigerant piping, 13...Liquid pipe, 14...Liquid injection tube.

Claims (1)

[Claims] 1. Air that is equipped with a compressor, a user-side heat exchanger, and a heat source-side heat exchanger, where the refrigerant in the heat-source-side heat exchanger is evaporated by exchanging heat with heat source water, and the air is heated by the user-side heat exchanger. In the harmonizer, a constant pressure expansion valve is provided on the inlet side of the heat source side heat exchanger during heating, and the opening degree of the valve is controlled by the refrigerant pressure at the outlet of the heat exchanger during heating. one end of the liquid injection tube is connected to the liquid tube on the inlet side during heating, and the other end of the liquid injection tube is connected to the outlet side of the heat source side heat exchanger during heating;
The tube is provided with a solenoid valve and a liquid injection valve, and when the discharge gas temperature is equal to or higher than a predetermined value, the solenoid valve is opened by a temperature-sensitive detection section that detects the discharge gas temperature of the compressor, and the other end of the tube is opened. An air conditioner characterized in that the opening degree of the liquid injection valve is adjusted depending on the temperature of the intake gas between a connected position and the compressor.